This sets the title "Elder" if your character had earned the title, otherwise it removes any active title.

/run local t={}; for titles=1,GetNumTitles()-1,1 do if IsTitleKnown(titles)==1 then table.insert(t,titles) end; end; local x=random(#t); print("Using title: "..GetTitleName(t[x])); SetCurrentTitle(t[x])

This macro will iterate over the list of titles, grab the ones the user has, then choose a random one from that list.